I haven't finished any paddles before but....You may want to try epoxy resin. You can't find anything much harder or more durable. You can paint on several thin coats, (sanding between coats) much like you would use polyurethane. The epoxy can then be varnished or polyurathaned to protect it from uv rays. If you use West Systems you can use their 207 hardener which contains UV filters. I've finished teak, mahogany, plywood and about anything else I find laying around this way. The finished product looks just like varnished wood and is basically bullet proof. You must top coat with something to protect from UV! The sun is to epoxy like criptonite is to superman. If left unprotected the epoxy will yellow become brittle and just fall apart. But if you protect it, it is some tuff stuff.
